图例定位

Question

这是我的数据和相应的ggplot

library(ggplot2)
library(ggnewscale)
library(cowplot)
library(ggalluvial)
library(patchwork)

data = 
structure(list(grp1 = c("X", "X", "X", "X", "Y", "Y", "Y", "Y"
), grp2 = c("A", "B", "C", "D", "A", "B", "C", "D"), val = c(1, 
2, 3, 4, 3, 4, 5, 6)), row.names = c(NA, -8L), class = "data.frame")

col_define = c('red', 'orange', 'blue', 'lightblue')
names(col_define) = c('A', 'B', 'C', 'D')

p <- ggplot(data, aes(x = grp1, group = grp2, y = val)) +
  geom_col(aes(fill = grp2)) +
  scale_fill_manual(values = col_define, breaks = c("A", "B"), name = "1") +
  new_scale_fill() +
  geom_col(aes(fill = grp2)) +
  scale_fill_manual(values = col_define, breaks = c("C", "D"), name = "2") +
  #guides(fill=guide_legend(order = 1, ncol = 2)) + 
  theme(legend.position="top", legend.direction = 'vertical')

p_legend <- cowplot::get_legend(p)

ggplot(data,
       aes(x = grp1, stratum = grp2, alluvium = grp2,
           y = val,
           fill = grp2)) +
  geom_flow(aes(fill = grp2), alpha = .3) +
  geom_stratum(aes(color = grp2), alpha = .9) +
  scale_fill_manual(values = col_define, breaks = names(col_define), aesthetics = c("color", "fill")) +
  guides(color = "none", fill = "none") +
  p_legend +
  theme(legend.position="top") +
  plot_layout(widths = c(50, 1))

我想把最后一个情节的传说放在地块窗口的顶部中心位置(即浅灰色区域)。我尝试了不同的输入，例如theme(legend.position="top")，但是这似乎不起作用。

是否有任何方法将图例位置固定在上面的情节窗口内的顶部中心位置？

注：

这个情节是根据我先前的文章中被接受的答案

Grouping legend of ggplot for stacked bar chart

Answer 1

将图例添加到绘图面板中的一个选项是使用patchwork::inset_element。

注1:我删除了legend.box.margin，并将legend.box.background填充设置为“白色”，但可以根据您的喜好随意调整。

注2:我在cowplot::ggdraw中包装了图例图，以删除图例周围的白色边距。

p <- ggplot(data, aes(x = grp1, group = grp2, y = val)) +
  geom_col(aes(fill = grp2)) +
  scale_fill_manual(values = col_define, breaks = c("A", "B"), name = "1") +
  new_scale_fill() +
  geom_col(aes(fill = grp2)) +
  scale_fill_manual(values = col_define, breaks = c("C", "D"), name = "2") +
  theme(legend.position="top", legend.direction = 'vertical', 
        legend.box.margin = margin(), 
        legend.box.background = element_rect(fill = "white", color = NA))

p_legend <- cowplot::get_legend(p)

p_main <- ggplot(data, aes(x = grp1, stratum = grp2, alluvium = grp2,
           y = val,
           fill = grp2)) +
  geom_flow(aes(fill = grp2), alpha = .3) +
  geom_stratum(aes(color = grp2), alpha = .9) +
  scale_fill_manual(values = col_define, breaks = names(col_define), aesthetics = c("color", "fill")) +
  guides(color = "none", fill = "none")

p_main + 
  inset_element(ggdraw(p_legend), right = .6, top = 1, left = .4, bottom = .9, clip = TRUE)

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